add active_runner_tasks and cancel old runners if no name is provided
Similar to what we do with the active_plotting_tasks
, I think that it is good to cancel the other unnamed runners by default, such that you don't run into problem if you execute runner = adaptive.Runner(learner)
a couple of times.
You can still have multiple runners at the same time, but you just have to name them, like:
runner1 = adaptive.Runner(learners, name='balancing_learners')
runner2 = adaptive.Runner(learner1D, name='learner1D')
Edited by Bas Nijholt